AlAs/GaAs(001) as a template for c-oriented hexagonal GaN grown by metalorganic vapor-phase epitaxy

Hexagonal GaN (h-GaN) layers are grown on GaAs(001) nominally singular subs trates with the assistance of thin AlAs layers. It is revealed that the cry stalline phases of GaN depend on the underlying GaAs-AlAs layered structure s; h-GaN can be grown on AlAs thicker than 9 nm, while cubic GaN on AlAs le ss than 9 nm. Furthermore, h-GaN can be grown on 20nm AlAs covered with GaA s thinner than 8 nm. Based on those results, it is proposed that the surfac e electronic structures of the GaAs-AlAs layered structures, rather than th e interface bonds, determine the crystalline orientations and phases of GaN . (C) 2000 Elsevier Science B.V. All rights reserved.